How water quality affects human health, or a few words about health risk assessment

The phrase health risk is encountered with increasing frequency in the nomenclature of both scientific papers, in everyday language, and in legal documents relating to the impact of used water on human health. The basis for this is the Water Law (2017), which, as one of the elements of the procedure for establishing protection zones for intakes, indicates the obligation to conduct a risk analysis that includes an assessment of health risks. In addition, the Health Ministry’s Regulation on the Quality of Water for Human Consumption (2017) cites consumer health safety.

Health risks-environmental risks: humans the source of the problem?

Water is an essential medium for human life – this is an undeniable fact. It provides the micro- and macronutrients necessary for development, growth, smooth operation of the metabolism and maintenance of the proper work of systems and organs, thus the life of the human body. However, it is no secret that the ingredients it contains can also exhibit undesirable negative effects on human health, including even carcinogenic (carcinogenic) ones. The World Health Organization (WHO) estimates that water that does not meet quality standards, lack of proper sanitation and inadequate hygiene are responsible for some 1.4 million deaths annually.

Contaminated water and poor sanitation have been linked to the transmission of the so-called “water pollution”. Waterborne diseases such as cholera, diarrhea, dysentery, hepatitis A, typhoid fever and polio. It is estimated that each year approx. 1 million people die from diarrhea, a largely preventable disease, and the deaths of 395,000. children under the age of 5 could be avoided if the aforementioned risk factors could be eliminated. In 2021. More than 251.4 million people required preventive treatment for schistosomiasis, an acute and chronic disease caused by parasitic worms that can be contracted through contact with infected water.

Progressive anthropopression on the environment brings with it an increase in the variety of xenobiotic pollutants, that is, of “human” origin. Newer and newer micropollutants are appearing (actually being detected!), which can be absorbed into organisms through water. The process of absorption can take place through direct contact with water or indirectly, through the trophic chain – into the human body from the environment(environmental risk).

Health exposure – how to bite it?

The potential occurrence of negative health effects after the use of water of a certain quality constitutes a so-called health risk. Probability assessment is a tool to estimate how water used for many years in a household may affect the health of its recipients. The indicated research method was developed by the US Environmental Protection Agency (US EPA 1989, 1991)) and has been used since the 1980s. last century. However, it is still not a widely used tool in the context of the security of collective water supply systems.

Of course, water treatment processes bring the various parameters to normative values, i.e. safe concentration levels, as required by the Ministry of Health Regulation (2017). On the other hand, assessing the potential health impact of water supplied to consumers “goes a step further.” In the procedure (US EPA 1989, 1991), there is a shift from the magnitude of the concentrations of substances to the magnitude of the doses of the elements in question taken into the body with the water as a result of many years of household use(residential scenario). Different exposure pathways are analyzed, which correspond to the different routes of contact with water. The most significant is the gastrointestinal route, that is, the exposure pathway through ingestion. Individual substances can also be absorbed through the skin – the dermal pathway (e.g., as a result of taking a bath), or taken by inhalation – the inhalation pathway (as a result of inhaling water vapors).

Quality of drinking water in Poland

In Poland, the quality of drinking water has improved significantly in recent decades. Water supply companies and the State Sanitary Inspectorate scrupulously control its parameters, which makes it possible to quickly detect and eliminate any risks. Evidence of the effectiveness of these measures is provided by available statistics.

Analyzing the information made available by the State Sanitary Inspectorate for 2022 and earlier years, note the continued improvement in drinking water quality, which was already at a high level. The data show that in 2006 about 91 percent of consumers received water that met quality standards, in 2009 this figure rose to about 93 percent, and in 2013. 96 percent of the population had access to compliant water. This trend continued in subsequent years. In 2014, about 98 percent of the population used water from a public supply that met the quality criteria set by the Ministry of Health. By 2022, this percentage had risen as high as 99.7 percent.

Health risks – different for children and adults

In order to estimate the doses taken by a given route, in addition to the different pathways of penetration of the parameters in question into the body, inter-individual variability between different groups of water consumers (age, gender) is also taken into account. These variations are due to differences in body weight, amount of water consumed, skin surface area, or the amount and length of bathing (the amount and duration of young children’s baths relative to the average time adults shower), among other factors (US EPA 1989, 1991).

Intake dose vs. reference dose

The calculated values of the doses received into the organisms as a result of the variants and sizes determined in this way are referred to the so-called. reference doses, that is, those specified for the carcinogenic and non-carcinogenic effects of the substance (US EPA 1989, 1991). These volumes are made available in a broad database developed by the US EPA.

The magnitude of the health risk is the quotient of the cumulative doses of substances ingested into the body and the reference doses for a given exposure pathway (oral, dermal, inhalation). In contrast, the aggregate health risk is the sum of the calculated magnitudes of exposure levels (risks) from all anlized scenarios (exposure pathways). (US EPA 1989, 1991). This procedure can be used as a test of water treatment processes and how long-term water from a given source affects the health safety of consumers (as long as we reduce the likelihood of negative health effects through the technological processes used).

In the article, I used, among others. From the works:

1. Law of July 20, 2017. Water Law (Journal of Laws 2017 item 1566, as amended).
2. US EPA 1989: Risk Assessment Guidance for Superfund, vol. 1: Human Health Evaluation Manual. Part A. Interim. Final. EPA/540/1-89/002. Washington, DC. USA: Office of Emergency and Remedial Response
3. US EPA.US EPA, 1991: Risk Assessment Guidance for Superfund, vol. 1: Human Health Evaluation Manual. Part B. Development of Risk-based Preliminary Remediation Goals. Interim. EPA/540R-92/003. Publication 9285.7-01B. Washington, DC. USA: Office of Emergency and Remedial Response
4. Order of the Minister of Health dated December 7, 2017. On the quality of water intended for human consumption (Journal of Laws 2017.2294, as amended).
5. https://www.who.int (accessed 02.01.2024).
6. https://www.gov.pl/web/gov/katalog-jednostek?catalogId=catalog-sanitary-station (accessed 02.01.2024).